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Robot Pollution-Control Boats Project

Robot Pollution-Control Boats Project

Boat-designation: Aeration Boat

UPDATE: please check out the related pollution-detection boat project!!

What problem does this boat address?

Most polluted rivers suffer from low levels of dissolved oxygen. Dissolved oxygen in a river can vary from 0 to 18mg/L. It’s generally accepted that 4-5mg/L are required to support a healthy population of fish; anything below 3mg/L will not be enough to ensure survival of fish, and levels lower than 4mg/L will negatively impact fish reproduction. All species have their own particular DO requirments: worms and fly larvae and algae can for instance tolerate low DO, whilst larger fish may require > 6mg/L

DOfish

Factors which effect levels of DO:

  1. Water temperature: higher temperatures will ‘push’ out the oxygen due to increased movement of water molecules [Note: polluted rivers often have reduced water, thus increased heating]
  2. Excessive bacteria from e.g. sewage: the bacteria require oxygen, thus will deplete the amount of DO present
  3. Fertilizer run-off: this will not only encourage plant growth in farms, but when entering a river it will encourage aquatic plant growth.  If the plant growth is so excessive that sufficient sunlight for photosynthesis is unable to reach the plants, they will instead take oxygen from the water! Thus depleting DO!

plants

How does the aeration boat address the problem?

The aeration boat will mitigate low-levels of DO induced by the factors mentioned via artificial surface aeration

This will be accomplished by fountains generated by pumps on boats. The fountains will increase contact between water and the atmosphere, thus transferring oxygen from the atmosphere into the water. The exchange of gases between aqueous and gaseous phases can be described as follows:

water3

More detail required: See https://srac.tamu.edu/index.cfm/event/getFactSheet/whichfactsheet/183/

Do we know that aeration really improves river and lake health?

In 1989, a study of water quality in an urban river and potential improvement using a prototype instream aerator, found:

As a result, a 2-year follow-up study and river monitoring was initiated. In both 1986 and 1987, late summer and early fall river conditions resulted in the potential for serious salmon kills, due to higher-than-normal river temperatures and very low dissolved oxygen. In both instances, the instream aerator prevented such fish kills in a key stretch of the river.

Paper: Effect of artificial aeration on the performance of vertical-flow constructed wetland treating heavily polluted river water. Link here
Paper: Managing cyanobacterial blooms by aeration Link here

Awkward questions

Would not a floating fountain that works with a large volume of water be more cost-effective and efficient than a small boat?

Specifications of the aeration boat

Example of aeration boat design (would be smaller) and video of solar pond aerator (obviously not robotic!!)

Solar_UFO

In addition to a pump which will be required for the fountain, the boat will require:

Electronics

  • Trolling motor ( electric motor, propeller and controls)
  • Adjustable rudder controlled by servos
  • Microcontrollers (x2) to handle navigation and sensors inc DO sensor and GPS
  • Does the boat require a transceiver (satellite or 3G) for communication?

Power

  • Solar panels for sunlight operation
  • A battery will be required for darkness operation (or the boat will be carried away downstream). It could potentially dock during the night.

Control Logic

  • Electric current sensors for motor and rudder (servo) to monitor for entanglements with aquatic plants, floating waste etc.
  • Accelerometers to monitor if boat has capsized
  • Real-time clock for time
  • Infrared sensor to detect light conditions
  • Dissolved oxygen sensor to decide if fountain is required. Or should fountain be always on during daylight?
  • Voltage divider circuit to monitor battery?
  • Collision avoidance sensors: ultrasonic, sharp IR?

Software – algorithms 

  • Robot boat needs to know where it is!
  • Robot boat needs memory of surroundings (i.e. location of river banks, islands)
  • Robot boat needs to plan a route
  • detection vs. avoidance of collisions: quad tree method?

Detailed notes for Robot Boat Subsystems

Please see the following pages:

1. Navigation and situational awareness

2. Sensors

3. Hull construction

4. Aeration device/fountain/pump

Discussion

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